Valve impact type dispensing pump

ABSTRACT

A dispensing pump, and more particularly, a valve impact type dispensing pump that may be used in a process of manufacturing an electronic product and may dispense an accurate amount of a liquid, such as a liquid synthetic resin, at high speed. The valve impact type dispensing pump can descend a valve rod at high speed and thus can dispense a liquid with high viscosity at high speed. The valve impact type dispensing pump can dispense an accurate amount of a liquid at high speed. Also, the valve impact type dispensing pump can dispense a liquid having high viscosity at high speed due to a fast descending speed of a valve rod.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57.

BACKGROUND

1. Field

The present disclosure relates to a dispensing pump, and moreparticularly, to a dispensing pump that may be used in a process ofmanufacturing an electronic product and may dispense an accurate amountof a liquid, such as a liquid synthetic resin, at high speed.

2. Discussion of Related Technology

Pumps for dispensing liquid are used in various technical fields, suchas processes of manufacturing electronic products by using semiconductorchips, and the like.

In particular, dispensing pumps are widely used in an underfill processof a semiconductor process. The underfill process is usually used in asurface mounting technique, such as a flip chip in which a plurality ofmetal balls are formed on a surface facing a substrate and whichelectrically connects the substrate and a semiconductor chip via theplurality of metal balls. If a liquid synthetic resin is applied onto acircumference of the semiconductor chip, the resin is dispersed into aspace between the semiconductor chip and the substrate by a capillaryphenomenon and is filled in a space between the metal balls. The resinthat fills the space between the semiconductor chip and the substrate ishardened so that adhesive strength between the semiconductor chip andthe substrate can be improved. In addition, the hardened resin serves asa shock absorber and dissipates heat generated in the semiconductorchip.

A function of dispensing a liquid at high speed of such dispensing pumpsbecomes significant. Korean Patent Laid-open Publication Nos.10-2005-0093935 and 10-2010-0045678 disclose a structure of a pump fordispensing a resin by ascending/descending a valve due to interactionbetween a cam and a cam follower. Such dispensing pumps according to therelated art have excellent performance but have a limitation in speed atwhich a valve rod descends due to a structure of cam protrusions of acam member and a structure of a roller. Thus, there are somedifficulties in dispensing the liquid at high speed, and in particular,it is difficult to dispense a liquid with high viscosity at high speed.

SUMMARY

One aspect of the present invention provides a valve impact typedispensing pump that may descend a valve rod at high speed and thus maydispense a liquid with high viscosity at high speed.

Another aspect of the present invention provides a valve impact typedispensing pump including: a pump body; a valve body including an inletpath on which a liquid from an outside is supplied, a reservoir in whichthe liquid supplied via the inlet path is stored, and a discharge pathon which the liquid stored in the reservoir is discharged, the valvebody being installed at the pump body; a valve rod pressurizing theliquid stored in the reservoir of the valve body and inserted in thereservoir of the valve body so that the liquid is discharged via thedischarge path; an operating rod connected to the valve rod and allowingthe valve rod to move relative to the valve body so that a relativemotion of the valve rod is allowed within a predetermined distance (gapdistance) in a lengthwise direction of the valve rod; a cam memberincluding through hole through which the operating rod passes and camprotrusions formed along a circumferential direction of the cam memberbased on the through hole and having inclined surfaces formed so that aheight of the cam protrusions increases, the cam member being installedat the pump body so that the cam member rotates around the through hole;a rotating unit rotating the cam member; a cam follower includingrollers that roll on the inclined surfaces of the cam protrusions whenthe cam member rotates, the cam follower coupled to the operating rodand allowing the valve rod to move relative to the valve body; and anelastic member installed between the pump body and the cam follower andproviding an elastic force to the cam follower so that the cam followerapproaches the cam member.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present inventionwill become more apparent by describing in detail embodiments thereofwith reference to the attached drawings in which:

FIG. 1 is a perspective view of a valve impact type dispensing pumpaccording to an embodiment of the present invention;

FIG. 2 is an exploded perspective view of main elements of the valveimpact type dispensing pump illustrated in FIG. 1;

FIG. 3 is a cross-sectional view taken along a line III-III of the valveimpact type dispensing pump of FIG. 1;

FIG. 4 is a cross-sectional view taken along a line IV-IV of the valveimpact type dispensing pump of FIG. 1;

FIGS. 5, 6, 7A, 7B, 8A, 8B, 9A, 9B, 10A, 10B, 11A and 11B are schematicviews for explaining an operation of the valve impact type dispensingpump of FIG. 1; and

FIG. 12 is a cross-sectional view of elements of a valve impact typedispensing pump according to another embodiment of the presentinvention.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will now be described more fullywith reference to the accompanying drawings in which exemplaryembodiments of the invention are shown.

FIG. 1 is a perspective view of a valve impact type dispensing pumpaccording to an embodiment of the present invention, FIG. 2 is anexploded perspective view of main elements of the valve impact typedispensing pump illustrated in FIG. 1, and FIG. 3 is a cross-sectionalview taken along a line III-III of the valve impact type dispensing pumpof FIG. 1.

Referring to FIGS. 1 through 3, the valve impact type dispensing pumpaccording to the present embodiment includes a pump body 100, a valvebody 110, a valve rod 210, an operating rod 220, a cam member 300, and acam follower 400.

The pump body 100 serves as a housing that supports the entire structureof the valve impact type dispensing pump. The pump body 100 is installedat a transfer device and is moved by the transfer device to allow aliquid to be dispensed.

The valve body 110 is installed at the pump body 100. The valve body 110includes an inlet path 111, a reservoir 112, and a discharge path 113.The liquid stored in an external syringe (not shown) flows to thereservoir 112 via the inlet path 111. The liquid stored in the reservoir112 is discharged via the discharge path 113 due to an operation of thevalve rod 210 that ascends/descends with respect to the reservoir 112. Anozzle 120 is connected to the discharge path 113 so as to adjustdispensing characteristics of the liquid.

The valve rod 210 is inserted in the reservoir 112 and pressurizes theliquid stored in the reservoir 112 so as to discharge the liquid via thedischarge path 113.

The cam member 300 is disposed above the valve body 110 and the valverod 210 and is installed at the pump body 100. The cam member 300 isinstalled at the pump body 100 so as to rotate around a virtual centralaxis that extends in a lengthwise direction of the valve rod 210. Abearing 130 is installed between the cam member 300 and the pump body100 so that the cam member 300 may rotate with respect to the pump body100.

The cam member 300 rotates by a rotating unit 900. The rotating unit 900includes a motor 910, a driving pulley 920, a timing belt 930, and adriven pulley 940. The motor 910 is installed at the pump body 100, andthe driven pulley 940 is installed at the cam member 300. The timingbelt 930 connects the driving pulley 920 and the driven pulley 940. Ifthe motor 910 allows the driving pulley 920 to rotate, the driven pulley940 rotates due to the timing belt 930. As a result, the cam member 300rotates.

The cam member 300 includes through hole 320 and a plurality of camprotrusions 310. The through hole 320 is formed to penetrate the centerof the disc-shaped cam member 300 in a vertical direction. The pluralityof cam protrusions 310 are arranged in a circumferential direction ofthe cam member 300 so that eight cam protrusions 310 are at the sameangle intervals (i.e., at intervals of 45 degrees). The cam protrusions310 are inclined in the same rotation direction along thecircumferential direction of the cam member 300. That is, the camprotrusions 310 include inclined surfaces 311 that are inclined so thatthe height (see h of FIG. 3) of the cam protrusions 310 may increasegradually clockwise, as illustrated in FIG. 2. Cross-sections of the camprotrusions 310 may be formed so that the inclined surfaces 311 aresteeply bent from their tops to lower portions. In the presentembodiment, the inclined surfaces 311 of the cam protrusions 310 areinclined from their tops in the vertical direction.

The operating rod 220 is disposed in the through hole 320 of the cammember 300 and is connected to the valve rod 210. The operating rod 220is coupled to the cam follower 400 and ascends or descends so that thevalve rod 210 may be moved up and down relative to the valve body 110.

The cam follower 400 faces a surface on which the cam protrusions 310 ofthe cam member 300 are formed and ascends/descends with respect to thecam member 300 due to interaction between the cam protrusions 310 andthe cam follower 400. The cam follower 400 includes two rollers 420 thatroll on the inclined surfaces 311 of the cam protrusions 310. Tworollers 420 of the cam follower 400 are disposed at intervals of 180degrees.

The cam follower 400 is spline-coupled to the pump body 100 via a splineshaft 440 so that an ascending/descending motion of the cam follower 400may be performed and relative rotation may be prevented. The camfollower 400 includes a spline boss 430 and is coupled to the pump body100 via the spline shaft 440 so as to make a linear motion(ascending/descending motion in the present embodiment) approaching thecam member 300 and not to allow relative rotation of the cam follower400.

An elastic member 600 is disposed between the cam follower 400 and thepump body 100 and provides an elastic force so that the cam follower 400approaches the cam member 300. In the present embodiment, the elasticmember 600 having a shape of a spring 600 is used. The cam follower 400receives the elastic force of the elastic member 600 and is maintainedto be closely adhered to the cam member 300.

The valve rod 210 and the operating rod 220 are connected to each otherby a gap member 500. The operating rod 220 is screw-coupled to the gapmember 500 and is fixed, and the valve rod 210 is connected to the gapmember 500 so that a relative motion of the valve rod 210 to the gapmember 500 may be allowed at a predetermined distance in a lengthwisedirection of the valve rod 210. The relative movable distance betweenthe gap member 500 and the valve rod 210 is referred to as a ‘gapdistance’ g.

In the present embodiment, the gap member 500 has a structureillustrated in FIGS. 2 through 4. A nut groove 501 is formed in an upperportion of the gap member 500 and is screw-coupled to the operating rod220. A tightening groove 502 is formed in the gap member 500 to passthrough the nut groove 501. A tightening hole 503 is formed in the gapmember 500 to perforate the tightening groove 502, and a tightening bolt504 is screw-coupled to an opposite portion to the tightening hole 503so as to pressurize the tightening groove 502 to reduce the size of thetightening groove 502 so that screw-coupling between the operating rod220 and the gap member 500 is not released.

A hanging groove 505 is formed in a lower portion of the gap member 500and has a T-shape so that the hanging groove 505 is open in a lateraldirection of the gap member 500. A hanging protrusion 211 is formed on atop end of the valve rod 210. The hanging protrusion 211 of the valverod 210 is slid on the hanging groove 505 of the gap member 500 in thelateral direction of the gap member 500 and is engaged therein so thatthe gap member 500 and the valve rod 210 may be connected to each other.Through the structure, the gap member 500 and the valve rod 210 may beconveniently coupled to or detached from each other. Also, since thevalve rod 210 is moved by the operating rod 220 and the gap member 500only in the vertical direction, the valve rod 210 is not detached fromthe gap member 500 while the valve rod 210 operates. Only when theoperating rod 220 ascends or the valve body 110 is detached from thepump body 100 in order to replace the valve rod 210, the valve rod 210is moved relative to the gap member 500 in a direction parallel to thehanging groove 505 so that the valve rod 210 may be easily detached fromthe gap member 500.

Since there is clearance corresponding to the gap distance g between thehanging grove 505 of the gap member 500 and the hanging protrusion 211of the valve rod 210, as described above, a time difference occursbetween the motion of the operating rod 220 and the motion of the valverod 210. That is, when the operating rod 220 ascends in a state where abottom surface of the gap member 500 and a top surface of the valve rod210 contact each other, only the operating rod 220 ascends by the gapdistance g in a state where the valve rod 210 stops, and if the hanginggroove 505 is caught in the hanging protrusion 211, the operating rod220 and the valve rod 210 ascend together. When the operating rod 220descends reversely in this state, only the operating rod 220 descends bythe gap distance g in a state where the valve rod 210 stops, and if thehanging groove 505 is caught in the hanging protrusion 211, theoperating rod 220 and the valve rod 210 descend together. Through thestructure of the hanging protrusion 211 and the hanging groove 505, thegap member 500 is connected to the valve rod 210 to interfere each otherwith the gap distance g allowed.

Hereinafter, an operation of the valve impact type dispensing pumphaving the above structure of FIGS. 1 through 3 will be described.

FIG. 4 is a cross-sectional view taken along a line IV-IV of the valveimpact type dispensing pump of FIG. 1, FIGS. 5 through 11A and 11B areschematic views for explaining an operation of the valve impact typedispensing pump of FIG. 1, and FIG. 12 is a cross-sectional view ofelements of a valve impact type dispensing pump according to anotherembodiment of the present invention.

Referring to FIG. 4, the liquid stored in the external syringe flows tothe reservoir 112 of the valve body 110 via the inlet path 111 underuniform pressure.

If the motor 910 operates in this state, the motor 910 rotates with thedriving pulley 920, and the driven pulley 940 that is connected to thedriving pulley 920 via the timing belt 930, also rotates. The cam member300 that is coupled to the driven pulley 940 rotates with the drivenpulley 940.

If the cam member 300 rotates, the rollers 420 of the cam follower 400roll along the inclined surfaces 311 of the cam protrusions 310, and thecam follower 400 ascends. Since the cam follower 400 is spline-coupledto the pump body 100, the cam follower 400 does not rotate but therollers 420 roll along the inclined surfaces 311 of the cam protrusions310 so that the cam follower 400 ascends. When the cam follower 400ascends, the elastic member 600 is pressurized while applying theelastic force to the cam follower 400 in a downward direction. Due tothe elastic force of the elastic member 600, the rollers 420 of the camfollower 400 are maintained in contact with a top surface of the cammember 300. The operating rod 220 coupled to the cam follower 400 alsoascends with the gap member 500. After the operating rod 220 and the gapmember 500 ascend by the gap distance g in a state where the valve rod210 stops, the hanging groove 505 is caught in the hanging protrusion211, and the valve rod 210 ascends with the operating rod 220 and is inthe state illustrated in FIGS. 3 and 4. When the valve rod 210 ascends,the liquid flows in a space formed in the reservoir 112, and the spaceis filled with the liquid.

If the rollers 420 roll along the inclined surfaces 311 of the camprotrusions 310 and pass through tops of the inclined surfaces 311 ofthe cam protrusions 310, the rollers 420 roll down due to the elasticforce of the elastic member 600. The cam follower 400, the operating rod220, and the valve rod 210 descend with the rollers 420. From theinstant that the operating rod 220 and the gap member 500 descend by thegap distance g in a state where the valve rod 210 stops and the hanginggroove 505 is caught in the hanging protrusion 211, the operating rod220 and the valve rod 210 descend together. The valve rod 210 descends,pressurizes the liquid filled in the space of the reservoir 112, anddischarges the liquid via the discharge path 113.

If the cam member 300 rotates consecutively and the rollers 420 ascendand descend along the cam protrusions 310 repeatedly, the valve rod 210ascends and descends consecutively while undergoing the above-describedprocedure so that the liquid may be discharged via the discharge path113.

In the above liquid-pumping mechanism, the descending speed of the valverod 210 greatly affects the discharge amount and discharge speed of theliquid. In order to adjust an accurate discharge amount, an innerdiameter of the discharge path 113 may be relatively small. As thedescending speed of the valve rod 210 increases, the liquid having highviscosity may be quickly dispensed via the discharge path 113 having asmall inner diameter. In particular, when the viscosity of the liquid ishigh, if the descending speed of the valve rod 210 is not sufficientlyhigh, due to resistance caused by viscosity and resistance of thedischarge path 113, the liquid may not be discharged. However, like inembodiments of the present invention, the gap member 500 is used so thata liquid having high viscosity may be dispensed. In this way, by usingthe valve impact type dispensing pump according to embodiments of thepresent invention, the range of the liquid that may be dispersed, may begreatly increased.

The descending speed of the valve rod 210 may be rapidly improved byusing a structure in which the gap member 500 and the valve rod 210 aremoved relative to each other by the gap distance g and are interlockedwith each other, as described above.

First, the relationship between the rotational speed of the cam member300 and the descending speed of the operating rod 220 will be describedwith reference to FIGS. 5 and 6.

The operating rod 220 starts to descend in a state where the rollers 420are disposed on the tops of the cam protrusions 310, as illustrated inFIG. 5. If the cam protrusions 310 are moved to the left by rotation ofthe cam member 300, the rollers 420 roll on the tops of the camprotrusions 310, and the operating rod 220 descends. The operating rod220 descends until the rollers 420 contact the lowermost portion of thetop surface of the cam member 300, as illustrated in FIG. 6.

When a radius of each roller 420 is r, a rotational angle of the roller420 is α, a substantial rotational radius of the cam member 300 withrespect to the roller 420 is R and a rotational angle of the cam member300 is θ, a horizontal movement distance xh at which the rollers 420 aremoved along a circumference of the cam member 300, may be expressedusing Equation 1:

x _(h) =r sin α=Rθ  (1).

A distance xv at which the rollers 420 descend from the tops of the camprotrusions 310 in the vertical direction may be expressed usingEquation 2:

x _(v) =r−r cos α  (2)

The horizontal movement distance xh of the rollers 420 obtained inEquation 1 may be differentiated with respect to time, as shown inEquation 3, in order to calculate a horizontal movement speed of therollers 420:

{dot over (x)} _(h) =r cos α{dot over (α)}=R{dot over (θ)}  (3)

Equation 3 will be summarized as Equation 4:

$\begin{matrix}{\overset{.}{\alpha} = {\frac{R}{r} \cdot {\frac{\overset{.}{\theta}}{\cos \; \alpha}.}}} & (4)\end{matrix}$

Equation 2 may be differentiated with respect to time and Equation 4 issubstituted for Equation 2 in order to calculate a speed at which therollers 420 descend from the tops of the cam protrusions 310 in thevertical direction, as shown in Equation 5:

$\begin{matrix}{{\overset{.}{x}}_{v} = {{r\; \sin \; {\alpha \cdot \overset{.}{\alpha}}} = {{r\; \sin \; {\alpha \cdot \frac{R}{r} \cdot \frac{\overset{.}{\theta}}{\cos \; \alpha}}} = {R\; \overset{.}{\theta}\tan \; {\alpha.}}}}} & (5)\end{matrix}$

According to the above Equation 5, the descending speed of the rollers420 and the operating rod 220 are proportional to tan α. If therotational speed of the cam member 300 is maintained constant by amotor, the descending speed of the operating rod 220 is substantiallydetermined by tan α. When α corresponding to the rotational speed of therollers 420 is 0, tan α starts from 0 and increases rapidly as αincreases. As a result, when the rollers 420 approach the lowermostportion of the top surface of the cam member 300 compared to the casethat the rollers 420 are moved around the cam protrusions 310, theoperating rod 220 descends at much higher speed. According toembodiments of the present invention, the descending speed of the valverod 210 is rapidly improved using a change of the descending speed ofthe operating rod 220. A detailed operating procedure thereof will bedescribed as below.

First, as illustrated in FIGS. 7A and 7B, the case that the operatingrod 220 and the valve rod 210 descend altogether and the rollers 420contact the lowermost portion of the top surface of the cam member 300,will be described. The top surface of the valve rod 210 and the bottomsurface of the gap member 500 contact each other, as illustrated in FIG.7B.

If the cam member 300 rotates in this state, the rollers 420 ascend, asillustrated in FIG. 8A. The operating rod 220 that is connected to therollers 420 ascends together. While the operating rod 220 ascends by thegap distance g, the valve rod 210 stops as illustrated in FIG. 8B.

If the operating rod 220 ascends by the gap distance g or higher, thehanging groove 505 of the gap member 500 and the hanging protrusion 211of the valve rod 210 are engaged in each other, and the operating rod220 and the valve rod 210 ascend together, as illustrated in FIGS. 9Aand 9B.

If the rollers 420 starts to descend from the tops of the camprotrusions 420, as illustrated in FIGS. 10A and 10B, while theoperating rod 220 is first moved by the gap distance g, only theoperating rod 220 descends in a state where the valve rod 210 stops, asillustrated in FIG. 10B. In this way, while the operating rod 220 ismoved at a relatively low speed within the range of the gap distance g,only the operating rod 220 descends, and the valve rod 210 does notdescend.

If the rollers 420 and the operating rod 220 are moved by the gapdistance g and ascend to some degree, the gap member 500 impacts thevalve rod 210 downwards and pressurizes the valve rod 210 downwards, asillustrated in FIGS. 11A and 11B. The rollers 420, the operating rod220, the gap member 500, and the valve rod 210 descend at higher speedthan in an area of the gap distance g.

As described above with reference to FIGS. 5 and 6, the descending speedof the rollers 420 increases in proportion to tan α as the rotationalangle α of the rollers 420 with respect to the tops of the camprotrusions 310 increases compared to in an initial stage. That is, asthe rollers 420 descend from the tops of the cam protrusions 310, thedescending speed of the rollers 420 increases rapidly. In the valveimpact type dispensing pump according to embodiments of the presentinvention, in a state where only the rollers 420 and the operating rod220 descend in the area of the gap distance g due to the gap member 500and the descending speed of the operating rod 220 increases, the gapmember 500 impacts the valve rod 210 and allows the valve rod 210 todescend at high speed.

If there is no gap member 500 and the operating rod 220 and the valverod 210 are fixed to each other, the valve rod 210 starts from thedescending speed of 0 to a final speed together with the operating rod220. However, by using the gap member 500 according to embodiments ofthe present invention, after only the operating rod 220 is moved and itsdescending speed increases in a state where the vale rod 210 stops, thegap member 500 collides with the valve rod 210 at high speed and allowsthe valve rod 210 to descend. A liquid having high viscosity may beeasily and quickly dispensed according to this principle.

The following Table 1 shows comparison of descending speeds of the valverod 210 with respect to several gap distances g that are calculatedusing the gap member 500. When the cam member 300 rotates with 1000 rpm(θ), the radius r of the roller 420 is 5 mm, the substantial rotationalradius R of the cam member 300 with respect to a center of the roller420 is 13 mm and the height h of the cam protrusions 310 is 2 mm, thedescending speeds of the valve rod 210 with respect to the gap distancesg are summarized as the following Table 1. As shown in Table 1, evenwhen a gap distance g of 0.3 mm is set to the height h of 2 mm of thecam protrusions 310, the average descending speed of the valve rod 210may be increased by 40% or higher compared to the case that the gapdistance g is 0.

TABLE 1 Circumferential Distance at Horizontal distance at which Averagewhich valve circumferential rollers 420 roll in a descending Gap rod 210distance at which range where valve Total time while speed of valvedistance g descends rollers 420 roll within rod 210 descends valve rod210 rod 210 (mm) (mm) gap distance g (mm) (mm) descends (usec) (mm/sec)0.0 2.0 0.00 4.00 2938 680.7 0.3 1.7 1.71 2.29 1685 1008.8 0.6 1.4 2.371.63 1191 1172.8 0.9 1.1 2.86 1.14 836 1315.7 1.2 0.8 3.25 0.75 5511451.4

The following Table 2 shows calculation of descending speeds of thevalve rod 210 when only the radius of the roller 420 is changed to 8 mmon the above-described same conditions.

TABLE 2 Circumferential Distance at Horizontal distance at which Averagewhich valve circumferential rollers 420 roll in a descending Gap rod 210distance at which range where valve Total time while speed of valvedistance g descends rollers 420 roll within rod 210 descends valve rod210 rod 210 (mm) (mm) gap distance g (mm) (mm) descends (usec) (mm/sec)0.0 2.0 0.00 5.29 3887 514.5 0.3 1.7 2.17 3.12 2293 741.5 0.6 1.4 3.042.25 1654 846.4 0.9 1.1 3.69 1.61 1179 933.0 1.2 0.8 4.21 1.08 7911011.0

Even in the above case, the descending speed of the valve rod 210 may beincreased by 40% or higher only by setting the gap distance g of 0.3 mmcompared to the case that there is no gap distance g. When the gapdistance g is set to 1.2 mm, the descending speed of the valve rod 210may be increased by about 100%.

Since the momentum and kinetic energy of the valve rod 210 areproportional to a descending speed of the valve rod 210 and a square ofthe descending speed, the liquid may be dispensed at much higher speedcompared to the related art. In particular, a liquid having highviscosity may be dispensed by a sufficient force via the discharge path113 having a relatively small inner diameter.

The above-described gap distance g may be greater than 0 and less thanthe height h of the cam protrusions 310. If the gap distance g is 0,there is no difference between the present invention and the relatedart. If the gap distance g is greater than the height h of the camprotrusions 310, the operating rod 220 cannot pressurize the valve rod210.

The height h of the cam protrusions 310 may be less than a value that isobtained by adding the length of the reservoir 112 to the gap distanceg. If not, the valve 210 may be excluded from the reservoir 112 of thevalve body 110.

Although embodiments of the present invention have been described asabove, the scope of the present invention is not limited to theabove-described embodiments.

For example, the gap member 500 is coupled to the operating rod 220, andthe valve rod 210 is moved relative to the gap member 500 by the gapdistance g but vice versa. The gap member 500 may be coupled to thevalve rod 210, and the operating rod 220 may be moved relative to thegap member 500 by the gap distance g while interfering with each other.In this case, the hanging protrusion 211 may be formed on the operatingrod 220 and is caught in the hanging groove 505 of the gap member 500.

Alternatively, the gap member 500 may be modified in various ways inwhich the valve rod 210 and the operating rod 220 may be moved relativeto each other to extend within the range of the gap distance g. Forexample, the gap member 550 having a shape of FIG. 12 may be used. Thegap member 550 may be configured in such a way that hanging protrusions251 and 261 are disposed on a valve rod 250 and an operating rod 260,respectively, and the hanging protrusion 251 of the valve rod 250 andthe hanging protrusion 261 of the operating rod 260 may be caught in thegap member 550. In this case, the gap member 550 is configured in such away that an upper member 551 and a lower member 552 of the gap member550 may be screw-coupled to each other, the hanging protrusion 261 ofthe operating rod 260 may be caught in the upper member 551 and thehanging protrusion 251 of the valve rod 250 may be caught in the lowermember 552. The upper member 551 and the lower member 552 that arescrew-coupled to each other, rotate relative to each other so that thegap distance g may be adjusted. When the gap distance g is set, relativerotation of the upper member 551 and the lower member 552 is preventedby a tightening bolt 553 so that the gap distance g may be fixed. Also,the upper member 551 of the gap member 550 may be screw-coupled to theoperating rod 260, or the lower member 552 of the gap member 550 may bescrew-coupled to the valve rod 250.

In FIGS. 1 and 2, eight cam protrusions 310 and two rollers 420 aredisposed. However, the number of cam protrusions 310 and the number ofrollers 420 may be diverse. The shape of the cam protrusions 310 mayvary according to their inclined angles and curvatures of inclinedsurfaces.

As described above, in a valve impact type dispensing pump according toembodiments of the present invention, a liquid may be dispensed at highspeed.

Also, the valve impact type dispensing pump according to the presentinvention may dispense a liquid having high viscosity at high speed dueto a fast descending speed of a valve rod.

While embodiments of the present invention have been particularly shownand described, it will be understood by those of ordinary skill in theart that various changes in form and details may be made therein withoutdeparting from the spirit and scope of the present invention as definedby the following claims.

1. A method of dispensing liquid, the method comprising: providing aliquid dispensing pump which comprises: a cam rotatable about arotational axis and comprising a cam surface around the rotational axis,a cam follower biased toward the cam surface and configured to travelalong the cam surface for reciprocating movement along a firstdirection, a coupler coupled to the cam follower to transfer thereciprocating movement of the cam follower to the coupler forreciprocating movement of the coupler with a stroke along the firstdirection, a valve assembly comprising a valve and a nozzle, and thecoupler further coupled to the valve with a gap therebetween such thatduring a first part of the stroke the coupler is movable relative to thevalve that does not transfer the reciprocating movement of the couplerto the valve and that during a second part of the stroke the couplercontacts the valve to transfer the reciprocating movement of the couplerto move the valve toward or away from the nozzle; supplying liquid tothe valve assembly; and rotating the cam about the rotational axis tocause the cam follower to travel along the cam surface for reciprocatingmovement thereof along the first direction, wherein as the coupler movesin the first direction toward the nozzle, the coupler first movesrelative to the valve within a distance of the gap along the firstdirection such that the movement of the coupler does not transfer anyforce to the valve and then the coupler contacts the valve and pushesthe valve toward the nozzle.
 2. The method of claim 1, wherein thecoupler comprises a coupler surface and the valve comprises a valvesurface, and the coupler surface moves toward the valve surface duringthe first part of the stroke until the coupler surface contacts thevalve surface.
 3. The method of claim 2, wherein during the second partof the stroke the coupler surface and the valve surface maintaincontacting each other such that the coupler pushes the valve toward thenozzle.
 4. The method of claim 2, wherein the coupler comprises a rodconnected to the cam follower, the rod comprising the coupler surface atits one end.
 5. The method of claim 2, further comprising a rod coupledto the cam follower and secured to the coupler with no relative motionof the rod relative to the coupler.
 6. The method of claim 2, whereinthe coupler comprises a second coupler surface and the valve comprises asecond valve surface, wherein during the second part of the stroke, thesecond coupler surface does not contact the second valve surface.
 7. Themethod of claim 6, wherein the second valve surface faces away from thevalve surface.
 8. The method of claim 6, wherein the second couplersurface contacts the second valve surface while the valve moves awayfrom the nozzle.
 9. The method of claim 6, wherein the distance of thegap between the coupler surface and the valve surface along the firstdirection has its maximum value when the second coupler surface contactsthe second valve surface.
 10. The method of claim 9, further comprisingadjusting the maximum value.
 11. The method of claim 1, wherein thedistance of the gap along the first direction is smaller than the strokeof the cam follower along the first direction.
 12. The method of claim2, wherein the cam surface comprises an ascending portion and adescending portion, wherein the coupler moves toward the nozzle alongthe first direction as the cam follower travels over the descendingportion, wherein during the cam follower's traveling over the descendingportion the coupler surface moves toward the valve surface and thencontacts the valve surface to push the valve toward the nozzle.
 13. Themethod of claim 2, wherein the cam surface comprises an ascendingportion and a descending portion, wherein the coupler moves away fromthe nozzle along the first direction as the cam follower travels on theascending portion, wherein the cam follower's traveling on the ascendingportion the coupler surface does not contact the valve surface.
 14. Amethod of making an electronic device, the method comprising: providingan intermediate electronic device comprising a surface on which to mountan electronic component; dispensing liquid on the surface of theintermediate electronic device, wherein dispensing liquid is performedusing the method of claim 1; and placing the electronic component overthe surface, wherein the liquid is disposed between the electroniccomponent and the surface.
 15. The method of claim 14, furthercomprising curing the liquid, thereby filling space between the surfaceand the electronic component by the cured liquid and bonding the surfaceand the electronic component.
 16. The method of claim 14, wherein thecoupler comprises a coupler surface and the valve comprises a valvesurface, and the coupler surface moves toward the valve surface duringthe first part of the stroke until the coupler surface contacts thevalve surface.
 17. The method of claim 16, wherein the coupler comprisesa second coupler surface and the valve comprises a second valve surface,wherein during the second part of the stroke, the second coupler surfacedoes not contact the second valve surface.
 18. The method of claim 17,wherein the second coupler surface contacts the second valve surfacewhile the valve moves away from the nozzle.
 19. The method of claim 16,wherein the cam surface comprises an ascending portion and a descendingportion, wherein the coupler moves toward the nozzle along the firstdirection as the cam follower travels over the descending portion,wherein during the cam follower's traveling over the descending portionthe coupler surface moves toward the valve surface and then contacts thevalve surface to push the valve toward the nozzle.
 20. The method ofclaim 14, wherein the distance of the gap along the first direction issmaller than the stroke of the cam follower along the first direction.